I read an article today whose author assumed that all lady schoolteachers who lived together in the early twentieth century did so because they were long-term lesbian lovers.
First off, the obvious. More than one woman in a house meant help with the rent, the grocery bill, and the housework. If they could afford a full-time servant or a part-time cleaning lady, it was also someone to share that expense (and outnumber the servant, if labor relations got tense). It was the same reason that single men who weren’t rich usually shared rooms with a friend or two or three. As the old saying goes, “two can live cheaper than one.”
Women schoolteachers, and women of many other professions and jobs, shared apartments and houses and boarding houses with other women because they were poor, were not living with their families, and wished to reduce the chance of scandal, rape, and murder. A woman living totally alone was a potential target. A woman living with other women had built-in chaperonage. She could discourage the burglar or the over-eager suitor, because she had witnesses around.
Teachers were in a particularly sensitive position, because many schools insisted that all women teachers be single, never married, constantly ladylike (ie, not constantly brandishing pistols and shotguns), and of spotless public character. If they lived alone, they had to guard their honor (and hence, their livelihoods!) from whispers. If they lived with relatives or with other single women, there were witnesses around.
Maiden ladies alone had only their force of character. Maiden ladies in twos or in gaggles could go places and do things with impunity. And they did.